How can a camera perform chemistry?

We might say it's a chemistry instrument and a camera. Basically, it uses a laser to determine a composition of the rocks or soils up to 25 feet away from the rover. The laser is focused down to a small spot on a target so that the energy of the laser shot can be really highly concentrated. Over a few billionths of a second this laser projects the energy of a million lightbulbs onto this small spotabout the size of a pinhead. That's a really high-power density. It creates a small plasma that erupts briefly, and ChemCam's telescope captures that light. The light travels down from the telescope into the body of the rover through an optical fiberwhich is an interesting detailand inside the body of the rover we have another part of the instrument where the colors of the plasma are recorded in great detail. We determine the composition of this target from the colors of that emitted light.

ChemCam also has a camera that takes pictures through the telescope so we can see intricate details of the rock or soil that the laser shot. We can see exactly where this little small spot hit.

So it's not only the laser spectroscopybeing able to see the rock also helps?

Absolutely. An interesting detail is that we kind of threw on the camera as a little added bonus, not thinking it was very important. We talked at times about removing the camera during the course of building this instrument. And now that we're on Mars and analyzing these targets, we've found that the camera is extremely important because it gives us the context of exactly what we shot. There are times where we try and shoot a very small object or feature and we need to know exactly whether we hit it or missed it.

And it's actually the highest-resolution imager on the rover. It's a remote imager, so it's just slightly higher resolution than the Mastcams. The best imaging we get out of the rover is a merger: We get the color from the Mastcams and then we get the detail from the ChemCam microimager. And that gives us the best resolution of anything on the rover for long distance.

Past rovers haven't had anything like ChemCam. How has this affected the way the science team plans experiments?

First of all, for long-range planning the rover team looks at the orbital imageswhich are really fantastic, and they're better than the previous rover generation hadand then we look at the Mastcam images that show us what's up [ahead] in the distance. But as we get close to somethingsay the rover is within 25 feet of some featuresthen we start shooting with ChemCam and looking to see where is the best, most interesting detail. What are these camera details that the Mastcam has seen are worth investigating? And then we start shooting at those.

So, just as an example, we started seeing veins in some of the images. We had actually started seeing chemical compositions before we saw the veins in the images, partly because ChemCam has one other detail that's really important: By using multiple laser shots we can uncover details. If there's stuff that's covered by dust you wont necessarily see it. So as we were going over some dusty areas we could see some of these calcium sulphate compositions, and we didn't know where they coming from until we could see the images of these veins. Then we shot at a vein and said, "Ah, yes, it's a vein of calcium sulphate."

Do you think something like ChemCam will be on the next Mars rover?

Yes there will be clearly something like it, because a rover experiment . . . you could describe it as sort of a funnel, where the remote sensing is at the top of the funnel. You need to survey the area around you, you need to get a lot of pictures to really see what's around, and potentially, take a lot of compositional measurements with a remote sensing instrument like ChemCam. The advantage of that is that you can take a lot of measurements quite rapidly, and then as you get close to something and want a high-accuracy or some kind of fine detail, that's when you get the arm instruments involved. But that takes longer and it takes more energy from the rover, more planning, etc.

How many measurements has ChemCam actually taken?

I was looking at some questions back on one of the public websites last night and someone was asking "We haven't seen a lot about ChemCam, is it still working?" And we've actually shot over 40,000 laser shots on Mars. We do a number of laser shots per observation but the reason they don't hear as much about it is that we're setting up and helping the team figure out where to do some of the more intricate measurements. Sometimes they'll get a little more of the publicity because they have greater accuracy. But we can say "Hey, this material here is going to be very interesting, you should drill here." They do that, and then they get to report some of the results sometimes. But as an architecture as a whole it's very critical for a rover mission.

A Part of Hearst Digital Media
Popular Mechanics participates in various affiliate marketing programs, which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites.